tbuckley/cabot-search huggingface dataset:
PB2262: PEGFILGRASTIM IN THE SUPPORTIVE CARE OF HEAVILY PRETREATED MULTIPLE MYELOMA IN POMALIDOMIDE-BASED TREATMENT
Authors: C. Cerchione, D. Nappi, A. E. Pareto, S. Ronconi, D. Cangini, M. Ceccolini, G. Musuraca, L. Catalano, G. Martinelli
Journal: HemaSphere (2022)

Background: Pegfilgrastim is a pegylated long-acting recombinant form of G-CSF that extends the half-life and allows for once-per-cycle dosing, requiring less frequent dosing than nonpegylated G-CSF. Aims: The objective of this study was to compare the efficacy and safety of pegfilgrastim in patients affected by heavily pretreated MM, treated with pomalidomide-dexamethasone, in order to determine whether a single subcutaneous injection of pegfilgrastim is as effective as daily injections of standard filgrastim, in terms of haematological toxicity, febrile neutropenic episodes, antibiotic usage and hospedalization duration. Methods: 57 patients (31 M/26 F), median age at diagnosis 69 years (r. 52-84), and median age at start of treatment 76 years (r.56-90) treated with several lines of treatments (median 7, r. 2-12), every refractory to all the drugs previously received, received Pomalidomide-Dexamethasone (P 4 mg for 21 days, D 40 mg days 1,8,15,22, pegfilgrastim day +8) every 28 days, until progression. Since first course, patients performed blood counts once weekly and received, from day +8 to day +19, prophylactic oral chinolonic antibiotics and anti-fungal drugs. During neutropenia after first cycle, Filgrastim (5 μgr/kg/day for 3 days) was given if neutrophils count was <1500 x 10^9 cells/L. Results: Median number of filgrastim administrations was 4.6 (r. 3-6); nadir neutropenia was registered after a median of 10.4 days (r. 7-14); median of nadir neutrophil count was 1.13 x 10^9 cells/L (r.0.3–1.5), with maximum duration of 14 days. From the second course, all patients switched to prophylaxis with pegfilgrastim (6 mg), injected subcutaneously with a single administration on day +3 independently from the neutrophil count at that time. During pegfilgrastim, neutropenia was never longer than 8 days, with a consequent reduction of neutropenia-related infections. Median nadir neutrophil count, evaluated for every patients for at least three courses of therapy (r. 3-6) registered at day +11, was 1.28 (r.0.9-2.2). Only 4 patients needed a supplement of 3 administrations of filgrastim. Summary/Conclusion: Pegfilgrastim was well tolerated in all patients: main side effects in our patients were mild fever and bone pain (21.2%). In patients affected by heavily pretreated MM treated with pomalidomide-dexamethasone, pegfilgrastim seems to reduce the incidence of severe neutropenia and infections and may increase the possibility to maintain the scheduled time of treatment.
P1658: DELAYED REVERSAL OF FACTOR V INHIBITOR ACTIVITY POST-IMMUNOSUPPRESSIVE THERAPY, FOLLOWED BY A SUCCESSFUL PREGNANCY: A CASE REPORT
Authors: A. Cegledi, I. Bodo, J. Dolgos, A. Varkonyi, B. Vilimi, G. Mikala
Journal: HemaSphere (2022)

Background: Acquired factor V inhibitor (AFVI) is a very rare autoimmune hemostatic disorder that leads to hemorrhagic manifestations of variable severity. Aims: We describe a case of a 35-year-old Caucasian female patient presenting with severe AFVI with life-threatening hemorrhages. The AFVI exhibited spontaneous reversal over several years after discontinuation of ineffective combination immunosuppressive therapies and subsequently a successful pregnancy. Methods: Diagnosis of AFVI was based on a marked prolongation of prothrombin time-international normalized ratio (INR) and activated partial thromboplastin time (APTI) not corrected by the addition of normal plasma (1:1 ratio), with FV activity reduced to <1.0%. Other coagulation factor activity levels were unchanged, and the presence of an FV inhibitor was revealed by the Bethesda inhibitor assay. Results: Over the course of 2.5 years, plasmapheresis plus immunoglobulins and different combination immunosuppressive regimens were adminstered (dexamethasone+rituximab; cyclophosphamide+dexamethasone + rituximab + cyclosporine; cyclosporine + sirolimus + cyclophosphamide + dexamethasone; bortezomib+sirolimus+methylprednisolone; sirolimus+mycophenolate mofetil). Coagulation could be effectively maintained using recombinant FVIIa. The combination immunosuppressive therapies resulted in intermittent reversal of AFVI over 2.5 years, which then became therapy-resistant. After discontinuation of the unsuccessful immunosuppressive therapies, the patient exhibited partial spontaneous remission: her FV activity gradually increased from ~1% to ~33% over the course of 5 years. The patient became pregnant and during her pregnancy, FV activity increased to 54%, and her coagulation parameters were normalized. She gave birth to a healthy child by Caesarean section without any bleeding complications. Summary/Conclusion: Patients with AFVI presenting with hemorrhagic manifestations should be treated aiming for hemostatic control as well as inhibitor eradication. The use of an activated bypassing agent for hemostatic control is effective in AFVI. The presented case is unique because the treatment regimens used included combinations of multiple immunosuppressive agents and also suggest that patients with AFVI resistant to combination immunosuppressive protocols receiving no therapy may undergo spontaneous remission. Long-term monitoring of the coagulation status and the anti-FV inhibitor levels is warranted.
P452: THE INTERACTOME OF CDK6 IN DIFFERENT ONCOGENIC CONTEXTS
Authors: L. Scheiblecker, S. Nebenfuehr, M. Zojer, E. Doma, V. Sexl, K. Kollmann
Journal: HemaSphere (2022)

Background: The mammalian cell cycle is controlled by a complex signaling network that is frequently deregulated in cancer. Cyclin-dependent kinases (CDKs) are the key players in governing cell cycle progression. CDK6 and its close homologue CDK4 are responsible for driving the cell cycle from G1 to S-Phase. In complex with their regulatory subunits, the D-type cyclins, CDK4/6 phosphorylate the retinoblastoma protein family members (Rb) to induce G1 to S-Phase progression and DNA replication. CDK6, and not CDK4, plays an important role in hematopoiesis and is frequently found overexpressed in hematologic malignancies. In the recent years, CDK6 has been shown to regulate transcription by interacting with chromatin in a kinase dependent and independent manner. This function is crucial in leukemia as well as hematopoietic stem cells. Aims: To better understand the transcriptional role of CDK6 in transformed and untransformed cells we will analyze the interactome of CDK6. We hypothesize that different oncogenes lead to the expression of different CDK6-dependent transcriptional programs and to different CDK6-containing protein complexes on DNA level. We aim to identify common and leukemia subtype-specific interaction partners of CDK6 that will represent novel therapeutic vulnerabilities in combination with CDK6 inhibition. Methods: To characterize the interactome of CDK6 we transformed the murine hematopoietic progenitor cell line HPC7 with the BCR-ABL or the MLL-AF9 oncogene that give rise to myeloid leukemia. We isolated CDK6-containing protein complexes by immunoprecipitation followed by mass spectrometry. To extend our data and to get a specific set of interaction partners involved in the transcriptional role of CDK6, we performed a nuclear fractionation prior to immunoprecipitation and mass spectrometry. This enabled us to focus on interaction partners solely in the nucleus. Results: We obtained proteins interacting with CDK6 on a global cell level as well as specific for the nucleus that represent co-factors of CDK6-mediated transcriptional regulation. By intersecting the proteomics data from transformed and untransformed HPC7 cells, we detected interaction partners of CDK6 that are common for all tested leukemia entities, specific for leukemic subtypes and interaction partners which just occur in untransformed cells. As a next step, the determined proteins will be subjected to pathway analysis to reveal CDK6 dependent signaling networks. These proteins might serve as valuable targets for potential combinatorial treatments together with CDK6 inhibition. Summary/Conclusion: Combining our results with next generation sequencing data will allow us deciphering the distinct transcriptional signatures regulated by CDK6 in different leukemia entities. Our insights will provide a better understanding of malignancies with enhanced CDK6 expression and may help to develop novel treatment strategies by interfering with CDK6 interaction partners.
PB2298: THE RELATIONSHIP BETWEEN PLATELET SPECIFIC ANTIBODIES AND THE SEVERITY OF NEWLY DIAGNOSED PEDIATRIC ITP
Authors: S. Dong
Journal: HemaSphere (2022)

Background: Immune thrombocytopenia (ITP) is an autoimmune mediated hemorrhagic disease characterized by thrombocytopenia. Platelet specific antibodies play a key role in platelet destruction. Aims: This study was aimed to determine whether platelet specific antibodies (including anti-GPIIb/IIIa, anti-GPIb/IX and anti-GPIa/IIa antibodies) are related to the severity of newly diagnosed pediatric ITP. Methods: This study retrospectively analyzed 154 newly diagnosed ITP patients from October 2016 to September 2021 in Beijing Children’s Hospital. Children who used only glucocorticoids during hospitalization were defined as Severity 1. Children who used glucocorticoids combined with intravenous immunoglobulin (IVIG) and/or single rhTPO were defined as Severity 2. Platelet specific antibodies were detected by PAKAUTO. Results: When the antibody levels were divided into positive and negative, children with positive anti-GPIIb/IIIa antibody are more severe than children with negative anti-GPIIb/IIIa antibody in newly diagnosed ITP (c2=3.969, P=0.046). When the antibody titer ratio was used to reflect the antibody levels, there was no significant difference between platelet specific antibodies and the severity of newly diagnosed pediatric ITP. Summary/Conclusion: Anti-GPIIb/IIIa antibody is a sign of higher severity in newly diagnosed pediatric ITP. anti-GPIb/IX and anti-GPIa/IIa antibodies were not found to be related to the severity of ITP.
Olfactory Dysfunction in Patients With Mild COVID-19 During Gamma, Delta, and Omicron Waves in Rio de Janeiro, Brazil
Authors: Cynthia Chester Cardoso, Átila Duque Rossi, Rafael Mello Galliez, Débora Souza Faffe, Amilcar Tanuri, Terezinha Marta Pereira Pinto Castiñeiras
Journal: JAMA (2022)

This study uses data obtained through an updated version of the Brazilian National Health System Questionnaire for COVID-19 to assess olfactory dysfunction in patients with mild COVID-19 in Rio de Janeiro, Brazil.
P1280: TARGETED INHIBITION OF DHODH IS SYNERGISTIC WITH BCL2 BLOCKADE IN LYMPHOMA WITH CONCURRENT MYC AND BCL2 REARRANGEMENT
Authors: W. Mo, L. Liu, M. Chen, Y. Qu, P. Wang, Y. Liang, X. Yan
Journal: HemaSphere (2022)

Background: Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin lymphoma, can be cured in approximately two-thirds of patients after initial therapy. The remaining one-third of patients have inferior survival outcomes due to relapse or refractoriness despite salvage chemotherapy with or without stem cell transplantation. The dual dysregulation of MYC and BCL2 is one of the most important pathogenic mechanisms. Thus, new therapies are needed to improve the prognosis of patients, and combined targeting of MYC and BCL2 appears to be a promising strategy. Dihydroorotate dehydrogenase (DHODH) is the fourth rate-limiting enzyme for the de novo biosynthesis of pyrimidine and has been shown to be a potential therapeutic target for multiple diseases. Recent data have demonstrated that DHODH inhibitors can target MYC in some tumors. Aims: To develop and assess new therapeutics, we investigated the effects of the DHODH inhibitor brequinar in DHL lymphoma cell lines and the synthetic effects of brequinar and venetoclax. Methods: We first investigated the activity of DHODH inhibition in genetically defined double-hit DLBCL(DHL) cell lines. We then investigated whether c-MYC could be repressed by brequinar in DHL cells. Then we tried to uncover the synergistic mechanism of brequinar and venetoclax. To understand the genome-wide effects and target genes of brequinar and the combination with venetoclax, we performed an RNA-seq of SU-DHL4 cells treated with brequinar, venetoclax, or the combination of both agents versus DMSO-treated cells. At last, we confirmed the synergistic effect of DHODH inhibition and BCL2 blockade in vivo. Results: DHODH inhibition could repress DLBCL cell lines with MYC and BCL2 abnormalities. The protein level of c-MYC was upregulated 6 hours after brequinar treatment and then downregulated gradually with prolonged treatment time. The gene levels of c-MYC decreased over time. The synergistic mechanism of brequinar and venetoclax is the complementarity of different pathways. RNA-seq of SU-DHL4 cells treated with different agents further implied the possible synergistic mechanism of the two agents. Finally, in vivo study confirmed targeted inhibition of DHODH is synergistic with BCL2 blockade in lymphoma with concurrent MYC and BCL2 rearrangement Summary/Conclusion: Our study demonstrates that combined blockade of DHODH and BCL2 could synergistically inhibit DLBCL with concurrent MYC and BCL2 abnormalities through multiple pathways. Thus, it can be reasonably expected that a clinical-grade DHODH inhibitor combined with venetoclax might improve outcomes for patients with DHL or double-expression lymphoma and other cancers with high expression of MYC and BCL2 or MYC and MCL-1. Our findings provide new insights into the molecular basis of this effect and offer opportunities to design new targeted treatments for lymphoma.
P627: COMBINED DRUG AND CRISPR/CAS9 SCREENING REVEALS SPECIFIC TARGETS FOR SF3B1- AND NOTCH1-MUTATED CLL CELLS
Authors: L. Dostálová, A. Ladungová, D. Škrnová, N. Varma Gottumukkala, Y. Lodhi, M. Smida
Journal: HemaSphere (2022)

Background: Chronic lymphocytic leukemia (CLL) is genetically heterogeneous disease with a plethora of mutations occurring in relatively low fraction of patients. Mutations in SF3B1 and NOTCH1 genes are among the most frequent recurrent mutations found in 10-20% CLL cases. The presence of these mutations is considered as a negative prognostic factor, yet, there is no specific treatment available to achieve more prominent response. Aims: The aim of this study was to use the combination of CRISPR/Cas9 screening and high-throughput drug screening on cells with introduced SF3B1 or NOTCH1 mutations in order to reveal unique vulnerabilities specific to the cells carrying these frequent CLL mutations. Methods: Using CRIPSR/Cas9-based homology directed repair, we have introduced specific mutations most recurrent within the hotspots of SF3B1 (K700E) and NOTCH1 (P2514fs) into CLL-derived cell line HG3. These two knock-in cell line variants were then subjected to a drug screening with a library of 859 approved drugs, enriched with oncology-indicated drugs. Cell viability in response to 10 uM library concentration upon 72h was assessed by Cell-Titer Glo and evaluated against the wild-type counterparts. Simultaneously, genome-wide CRISPR/Cas9 knockout screen was performed in these cell lines to identify genes whose deletion is selectively lethal to SF3B1 or NOTCH1-mutated cells. Results: The CRISPR/Cas9 dropout screen has revealed several interesting genes that are in synthetic lethal relationship with the introduced point mutations. In particular, SPDYE1, a gene involved in cell cycle regulation, and LUC7L3, involved in splicing and cAMP regulatory element binding, were found to be synthetically lethal with the NOTCH1 mutation. On contrary, SNUPN, responsible for transport of spliceosomal snRNPs, and UQCRC1, involved in cytochrome c regulation and oxidative phosphorylation, were found to be essential for SF3B1-mutated cells. Drug screening using library of approved drugs demonstrated general hypersensitivity of both the mutant cell lines and the wild-type controls to the inhibitors of proteasome and HDAC enzymes. In addition, exquisite sensitivity of NOTCH1-mutant and SF3B1-mutant cell lines, contrary to their wild-type counterparts, was revealed towards the inhibitors of various hormone receptors or inhibitors of 20S proteasome. Summary/Conclusion: The combination of diverse screening approaches may reveal novel vulnerabilities specific for individual mutations frequently recurring in CLL patients. Thorough validations of the identified hits is ongoing, together with the analyses into the possible mechanisms behind these unique targets. This research was partly financed by the grant MUNI/A/1330/2021, MUNI/IGA/1516/2020 and MUNI/A/1419/2021.
P311: IMBALANCES IN HOMOCYSTEINE METABOLISM AND LEUKEMIA
Authors: N. Bouayed Abdelmoula
Journal: HemaSphere (2022)

Background: The correlation between imbalances in homocysteine metabolism and leukaemia is a matter of debate. While the effects of polymorphisms of key homocysteine metabolism enzymes on homocysteinemia are confirmed, their direct causality in the genesis of leukaemias or their role as disease markers (diagnostic or prognostic) remains controversial. It has been reported in several studies that the C677T and A1298C polymorphisms of the MTHFR may play a role in the pathophysiology of acute leukaemias and various other types of signalopathies such as cancers. Homocysteine could indeed modulate the expression of certain tumour suppressor genes and induce epigenetic alterations. Aims: In this work, the aim was to identify this correlation using a molecular study of MTHFR polymorphisms in a Tunisian cohort with acute lymphoblastic leukemia. Methods: The molecular study involved a cohort of 41 Tunisian children with acute lymphoblastic leukemia. Genomic DNA was extracted from blood samples. Amplification of the regions of interest of the MTHFR gene at exons 4 and 7 was performed by PCR using primers designed in silico. Genotyping of the 677C>T and 1298 A>C polymorphisms was performed by PCR-RFLP of the amplicons using two restriction enzymes HinfI and MboII. Results: MTHFR polymorphisms were detected in 39% of the children. The frequency of polymorphic alleles corresponded to 15.85% for the A1298C polymorphism and 4.87% for the C677T polymorphism. In fact, The C677T and A1298C MTHFR polymorphisms were detected in respectively 4 and 11 patients as heterozygous. Only one patient harbored homozygous A1298C MTHFR polymorphism. Only two cases were heterozygotes for both polymorphisms. Summary/Conclusion: Imbalances in MTHFR homocysteine metabolism associated with the polymorphisms do not appear to be a risk factor for ALL in the study cohort.
P1668: SYNERGY OF RED BLOOD CELLS AND TRANEXAMIC ACID IN THE INHIBITION OF FIBRINOLYSIS
Authors: A. Raska, K. Kalman, B. Egri, I. Roberts, K. Kolev, N. Wohner
Journal: HemaSphere (2022)

Background: Postpartum haemorrhage (PPH) is the leading cause of maternal death world-wide. Maternal anaemia strongly increases the risk of PPH. The Woman trial showed that the antifibrinolytic tranexamic acid (TXA) reduces PPH deaths. The Woman-2 trial is now assessing whether TXA can prevent PPH in anaemic women. Low RBC-counts promote fibrinolysis by altering fibrin structure and plasminogen activation. We explore the effect of low RBC counts on the potency of TXA. Aims: To examine if the RBC content of fibrin clots affects the anti-fibrinolytic potency of TXA. Methods: We used ball sedimentation assay (BS) and elastic motion thromboelastography (ClotPro) to monitor the lysis of fibrin containing plasminogen and tissue-type plasminogen activator (tPA) at various RBC-counts and TXA concentrations. We examined the anti-fibrinolytic potency of TXA with parallel line bioassay analysis of lysis times and with dose-response curves of lysis inhibition, over a range of tPA and TXA concentrations. Results: Compared to RBC-free fibrin, the anti-fibrinolytic potency of 4–64 µM TXA was increased in the presence of RBC at 10–40% (V/V). This effect was consistent at all TXA concentrations and RBC counts in both BS and ClotPro assays. The maximal increase in TXA potency was 2.7-fold at 64 µM TXA and 20% (V/V) RBC (Fig.1A). The prolongation of lysis time in response to varying TXA concentration indicated that RBC increased the number of target sites available for TXA binding (Lt max in Fig.1B) without any significant change in the TXA concentration needed to achieve a half-maximal effect (K s in Fig.2B). These extra TXA binding sites are probably presented by the higher fraction of plasmin residing in unbound form in a fibrin meshwork of thinner fibers which is formed in the presence of RBCs. Image:Summary/Conclusion: RBCs increase the anti-fibrinolytic potency of TXA. Higher doses of TXA may be required to inhibit fibrinolysis in severely anaemic women.
PB2300: COMPLEMENT ACTIVATION NEGATIVELY AFFECTS THE PLATELET RESPONSE TO THROMBOPOIETIN RECEPTOR AGONISTS IN PATIENTS WITH IMMUNE THROMBOCYTOPENIA: A PROSPECTIVE COHORT STUDY
Authors: A. Åkesson, J. B. Bussel, M. Martin, A. M. Blom, J. Klintman, W. Ghanima, E. Zetterberg, L. Garabet
Journal: HemaSphere (2022)

Background: Increased platelet destruction is central in the pathogenesis of immune thrombocytopenia. However, impaired platelet production is also relevant, and its significance underlies the rationale for treatment with thrombopoietin receptor agonists (TPO-RAs). Previous studies have associated enhanced complement activation with increased disease severity. Additionally, treatment refractoriness has been demonstrated to resolve by the administration of complement-targeted therapeutics in a subset of patients. Aims: To investigate the association between complement activation and platelet response to TPO-RA therapy. Methods: In this study, blood samples from patients with chronic immune thrombocytopenia (n = 15) were prospectively collected before and 2, 6 and 12 weeks after the initiation of TPO-RA therapy. Levels of complement degradation product C4d and soluble terminal complement complexes were assessed. Results: Patients with significantly elevated baseline levels of terminal complement complexes had more often undergone splenectomy (p = .08), exhibited more often an inadequate platelet response (p = .04) and were exclusively subjected to rescue therapy with intravenous immunoglobulin (p = .02) during the study period. C4d showed a significant (p = .01) ability to distinguish samples with significant terminal complement activation, implying engagement of the classical complement pathway. Summary/Conclusion: Elevated levels of complement biomarkers were associated with a worse TPO-RA treatment response. Larger studies are needed to confirm these results. Biomarkers of complement activation may prove valuable as a prognostic tool to predict which patients that potentially could benefit from complement-inhibiting therapy in the future.